title: Blastocyst transfer in day-5 embryo transfer depends primarily on the number of oocytes retrieved and not on age.
abstract: OBJECTIVE
  To analyze the effects of patient age and treatment cycle number on the occurrence of blastocyst transfer and subsequent implantation.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Department of endocrinology and reproduction.
  
  
  METHODS
  All 1,099 women had day-5 transfers after IVF or intracytoplasmic sperm injection treatment.
  
  
  METHODS
  All patients were checked for embryo development in vitro in consecutive day-5 transfer cycles. Two blastocysts or three lesser-developed embryos were transferred.
  
  
  METHODS
  Blastocyst formation rate or clinical pregnancy/implantation rate.
  
  
  RESULTS
  Of 929 patients in the first cycle, 545 (59%) had at least one blastocyst available for ET. Among 151 patients with a blastocyst in cycle 1, 77 developed one or more blastocysts in cycle 2 (51%). Fifty of 143 patients without a blastocyst in cycle 1 had at least one blastocyst in cycle 2 (35%). After subdivision of all day-5 ETs according to the first four cycles, the following implantation rates per embryo were found for ET with one or more blastocysts: cycle 1 (n = 545), 23%; cycle 2 (n = 264), 23%; cycle 3 (n = 110), 14%; and cycle 4 (n = 27), 12%, and with noncavitating embryos, respectively: (n = 384) 6%, (n = 193) 6%, (n = 94) 2%, and (n = 35) 3%. The negative correlation of the age of the woman on blastulation depended primarily on the number of oocytes retrieved.
  
  
  CONCLUSIONS
  The blastocyst implantation rate decreased after cycle 2. Biologic ovarian age, rather than chronologic age, determines the frequency of blastocyst transfer or pregnancy rate.
authors.affiliation: Department of Endocrinology and Reproduction, Erasmus University Rotterdam, The Netherlands.
authors.forename: M C
authors.initials: MC
authors.lastname: Scholtes
authors.forename: G H
authors.initials: GH
authors.lastname: Zeilmaker
mesh_terms: D000328:Adult; D000375:Aging / Q000502:physiology*; D001755:Blastocyst; D003593:Cytoplasm; D010064:Embryo Implantation; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D008297:Male; D008845:Microinjections; D008875:Middle Aged; D009865:Oocytes; D011247:Pregnancy; D018873:Pregnancy Rate; D011446:Prospective Studies; D013048:Specimen Handling; D013094:Spermatozoa; D013997:Time Factors